feat(dashboard,core): warn before project creation when git is missing

Registering a project on a git-less host used to fail after submission
with a raw spawn error. The setup wizard now probes gitCli up front and
offers: open the Git downloads (picked up without restart thanks to the
stale-PATH resolver), create the project anyway without a git repo
(new skipGitInit passthrough, rejected for clone mode), or cancel.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packages/dashboard/app/api/legacy.ts

@@ -6290,6 +6290,8 @@ export interface ProjectCreateInput {
   cloneUrl?: string;
   workspaceMode?: boolean;
   taskPrefix?: string;
+  /** Confirmed "create anyway without a git repo" when git is missing on the host (never valid for clone mode). */
+  skipGitInit?: boolean;
 }
 
 export type DockerNodeConfigInfo = DockerNodeConfig;